CN110534722B - A kind of preparation method of multi-cavity cladding structure bismuth sulfide/cobalt sulfide composite electrode material - Google Patents

Abstract

The invention discloses a novel multi-cavity coating structure bismuth sulfide/cobalt sulfide composite electrode material and a preparation method thereof. The method is simple and easy to implement, has wide applicability, and can have wide application prospect in the fields of lithium ion batteries, sodium ion batteries, potassium ion batteries and the like.

Description

A kind of preparation method of multi-cavity cladding structure bismuth sulfide/cobalt sulfide composite electrode material

technical field

The invention relates to a bismuth sulfide/cobalt sulfide composite electrode material with a multi-cavity coating structure and a preparation method thereof, belonging to the technical field of battery electrode material preparation.

Background technique

Lithium-ion batteries have been widely used in portable electronic devices and hybrid electric vehicles, but the theoretical capacity of industrial graphite anodes is too low, and there is an urgent need to find high-performance anode materials for lithium-ion batteries and lithium-ion batteries. In recent years, bismuth sulfide (Bi ₂ S ₃ ) anode has attracted great attention due to its high theoretical mass capacity and extremely high volume capacity. However, the large-capacity Bi ₂ S ₃ negative electrode has severe volume expansion during the reaction process of the lithium-ion battery, and loses electrical contact with the current collector, resulting in rapid capacity decay. Therefore, constructing an excellent mechanism to alleviate the volume expansion of the negative electrode during cycling appears to be especially important.

The application of hollow structures in lithium-ion batteries has obvious advantages, which can increase the contact area of active materials and electrolytes, which is beneficial to mass and charge transfer, and accelerates the reaction speed, especially compared with simple hollow structures, multi-shell or The complex hollow structure with multiple cavities can better accommodate the volume expansion induced during the cycling of Li-ion batteries. Therefore, it is of great significance to use a complex hollow structure as the outer layer for surface coating _{of Bi2S3} anode, which can improve the cycling performance of Li-ion batteries and improve the reaction efficiency of the battery during cycling.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a simple and feasible multi-cavity coating structure bismuth sulfide/cobalt sulfide composite electrode material preparation method in order to overcome the deficiencies in the prior art, and select a certain proportion of bismuth nitrate at a certain temperature. The bismuth oxybromide spheres were synthesized with potassium bromide, and then the metal organic framework polyhedron ZIF-67 was uniformly coated on the surface of the bismuth oxybromide spheres. Bismuth sulfide/cobalt sulfide electrode material coated with hollow cavity. Compared with the traditional graphite electrode, the multi-cavity coating structure bismuth sulfide/cobalt sulfide composite electrode material prepared by the invention can relieve the expansion of the bismuth sulfide core during the cycle process, and the cobalt sulfide in the outer layer can contribute to the energy density. , the method is simple and feasible, and the cost is low, and it has a wide range of applications, and can have a great application prospect in the fields of lithium ion batteries, sodium ion batteries and potassium ion batteries.

For achieving the above object, the present invention adopts the following technical scheme to be:

(1) Dissolve 0.3-0.6 g of bismuth nitrate pentahydrate and 0.3-0.5 g of polyvinylpyrrolidone in 20 mL of ethylene glycol, and then add 0.08-0.1 g of potassium bromide to the above mixture to obtain a suspension;

(2) Then transfer the mixture of step (1) to the reaction kettle and seal it, keep it at a temperature of 100 ℃ to 150 ℃ for 10 to 12 h, and after it cools down to room temperature naturally, wash it by centrifugation with absolute ethanol for 3-5 hours. time, the product after washing is dried to obtain bismuth oxybromide ball;

(3) Stir and dissolve 30-50 mg of bismuth oxybromide spheres obtained in step (1), 1-2 g of polyvinylpyrrolidone and 0.5-0.8 g of cobalt nitrate hexahydrate in 20 mL of methanol. -The methanol of methylimidazole is slowly dropped into the above-mentioned mixture and stirred, and the nucleation growth of the crystal is used to nucleate evenly on the surface active site of the bismuth oxybromide sphere, and then it grows continuously, wraps the inner sphere, and finally forms a After stirring for 20 to 30 minutes, the obtained purple powder product was collected by centrifugal filtration, washed with deionized water and ethanol for 3 to 5 times and dried;

(4) Dissolve 100-300 mg of thioacetamide in 15-30 mL of ethanol, weigh 40-60 mg of the purple powder product obtained in step (3), add it to the above ethanol solution, transfer it to the reaction kettle, and lock it. Tightly, at a constant temperature of 150-180 °C in an oven, keep the temperature for 3-4 hours, use anion exchange, sulfide ions replace the organic ligands in the metal organic framework and the bromine and oxygen of bismuth oxybromide to obtain cobalt sulfide and bismuth sulfide, and finally Centrifugal filtration, collecting the obtained powder product, washing with deionized water and ethanol 3 to 5 times and drying;

(5) Weigh 50-80 mg of the powder product obtained in step (4), spread it evenly in a porcelain boat, and then place the porcelain boat in a tube furnace protected by argon and hydrogen gas for calcination at a calcination temperature of 200-500 °C. Heat preservation for 1 to 5 hours; finally, the multi-cavity coated bismuth sulfide/cobalt sulfide composite electrode material is prepared after it is naturally cooled to room temperature.

The significant advantages of the present invention are:

The preparation method of the bismuth sulfide/cobalt sulfide electrode material with a multi-cavity coating structure provided by the present invention utilizes the method of uniform nucleation and growth of MOF materials in a solution, and skillfully introduces bismuth oxybromide spheres so that the MOF materials are uniformly coated on the surface of the spheres. Then, through the hydrothermal vulcanization process, the inner bismuth oxybromide ball and the outer MOF are vulcanized to obtain a multi-cavity cladding structure, and finally calcination is performed to improve the crystal form to obtain a multi-cavity cladding structure bismuth sulfide/cobalt sulfide electrode material . Compared with the traditional commercial graphite negative electrode, the multi-cavity coated bismuth sulfide/cobalt sulfide electrode material prepared by the invention has higher energy density, and can alleviate the volume expansion during the cycle, thereby obtaining excellent cycle performance. The method is simple, easy to implement, low in cost, has wide applicability, and has great application prospects in the fields of lithium ion batteries, sodium ion batteries and potassium ion batteries.

Description of drawings

1 is a scanning electron microscope image of the multi-cavity cladding structure bismuth sulfide/cobalt sulfide composite electrode material prepared in Example 1;

Fig. 2 is the scanning electron microscope picture of the bismuth oxybromide ball coating MOF precursor that embodiment 2 makes;

Fig. 3 is the scanning electron microscope image of the oxybromide ball-coated MOF precursor prepared in Example 3;

4 is an X-ray diffraction analysis pattern of the multi-cavity cladding structure bismuth sulfide/cobalt sulfide composite electrode material prepared in Example 1;

5 is an energy spectrum distribution scan diagram of the multi-cavity cladding structure bismuth sulfide/cobalt sulfide composite electrode material prepared in Example 1;

6 is a graph showing the cycle performance of the multi-cavity coated bismuth sulfide/cobalt sulfide composite electrode material prepared in Example 1 as a negative electrode material for a lithium ion battery under the condition of a current density of 100 mA g ⁻¹ ;

Figure 7 is the rate performance of the multi-cavity cladding bismuth sulfide/cobalt sulfide composite electrode material prepared in Example 1 as a negative electrode material for lithium ion batteries at different current densities;

Figure 8 is a graph showing the cycle performance of the multi-cavity coated bismuth sulfide/cobalt sulfide composite electrode material prepared in Example 1 as a negative electrode material for a sodium-ion battery at a current density of 100 mA g ^-1 ;

Figure 9 shows the rate performance of the multi-cavity coated bismuth sulfide/cobalt sulfide composite electrode material prepared in Example 1 as a negative electrode material for a sodium-ion battery at different current densities.

Detailed ways

The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to these embodiments.

Example 1

(1) Dissolve 0.6 g of bismuth nitrate pentahydrate and 0.3 g of polyvinylpyrrolidone (PVP K30) in 20 mL of ethylene glycol, and then add 0.08 g of potassium bromide to the above mixture to obtain a suspension.

(2) The mixture of step (1) was then transferred to the reactor and sealed, and kept at 150 °C for 12 h. After it was naturally cooled to room temperature, it was centrifuged and washed three times with absolute ethanol. Drying to obtain bismuth oxybromide balls.

(3) 50 mg of bismuth oxybromide spheres obtained in step (1), 1 g of polyvinylpyrrolidone (PVP K30) and 0.7 g of cobalt nitrate hexahydrate (Co(NO ₃ ) ₂ ·6H ₂ O) were stirred in 20 mL of methanol After dissolving, 20 ml of methanol containing 0.8 g of 2-methylimidazole was slowly dropped into the above mixture and stirred. After stirring for 30 minutes, the obtained product was collected by centrifugal filtration, and washed three times with deionized water and ethanol.

(4) Dissolve 250 mg of thioacetamide in 15 mL of ethanol, weigh 40 mg of the purple powder product obtained in step (3), add it to the above ethanol solution, transfer it to the reaction kettle, lock it tightly, and place it in an oven for 180 At a constant temperature of ℃, the temperature was kept for 4 hours, and finally the powder was collected by centrifugal filtration, washed three times with deionized water and ethanol, and dried.

(5) Measure 50 mg of the powder product obtained in step (2), spread it evenly in a porcelain boat, and then place the porcelain boat in a tube furnace protected by argon and hydrogen for calcination at a calcination temperature of 350 °C and hold for 3 hours. Finally, the multi-cavity coating structure bismuth sulfide/cobalt sulfide composite electrode material can be prepared after it is naturally cooled to room temperature; it can be seen from the scanning electron microscope image in Figure 1 that the multi-cavity coating structure particles are uniform in size and uniform in dispersion; It can be seen from the X-ray diffraction analysis pattern in Figure 4 that the diffraction peaks of the sample correspond to the cobalt sulfide and bismuth sulfide diffraction card peaks one-to-one, and it is determined that the composite material of cobalt sulfide and bismuth sulfide is obtained; from the energy spectrum distribution of Figure 5 It can be found from the scanning diagram that the obtained elements sulfur, cobalt and bismuth are uniformly distributed in the sample; Figure 6 shows the cycle performance of the above composite electrode material as the negative electrode material of lithium ion battery under the condition of current density of 100 mA g ^-1 , after 800 cycles Cycling, the capacity has almost no decay, proving the excellent cycling performance of the bismuth sulfide/cobalt sulfide composite electrode material.

Example 2

(1) Dissolve 0.5 g of bismuth nitrate pentahydrate and 0.4 g of polyvinylpyrrolidone (PVP K30) in 20 mL of ethylene glycol, and then add 0.1 g of potassium bromide to the above mixture to obtain a suspension.

(2) The mixture of step (1) was then transferred to the reactor and sealed, and kept at 120 °C for 12 h. After it was naturally cooled to room temperature, it was centrifuged and washed three times with absolute ethanol. Drying to obtain bismuth oxybromide balls.

(3) Dissolve 50 mg of bismuth oxybromide spheres obtained in step (1), 2 g of polyvinylpyrrolidone (PVP K30) and 0.8 g of cobalt nitrate hexahydrate (Co(NO ₃ ) ₂ ·6H ₂ O) in 20 mL of methanol Stir to dissolve, slowly drop 20 ml of methanol containing 0.9 2-methylimidazole into the above mixture and stir, after stirring for 5 minutes, the obtained product is collected by centrifugal filtration, and washed three times with deionized water and ethanol.

(4) Dissolve 250 mg of thioacetamide in 15 mL of ethanol, weigh 40 mg of the purple powder product obtained in step (3), add it to the above ethanol solution, transfer it to the reaction kettle, lock it tightly, and place it in an oven for 180 At a constant temperature of ℃, the temperature was kept for 4 hours, and finally the powder was collected by centrifugal filtration, washed three times with deionized water and ethanol, and dried.

(5) Measure 50 mg of the powder product obtained in step (3), spread it evenly in a porcelain boat, and then place the porcelain boat in a tube furnace protected by argon and hydrogen for calcination at a calcination temperature of 350 °C and hold for 2 hours. Finally, the multi-cavity cladding structure bismuth sulfide/cobalt sulfide composite electrode material can be prepared after it is naturally cooled to room temperature. From the scanning electron microscope image of the MOF precursor coated with bismuth oxybromide spheres in Figure 2, with the shortening of the coating time, the MOF particles are smaller.

Example 3

(1) Dissolve 0.4 g of bismuth nitrate pentahydrate and 0.2 g of polyvinylpyrrolidone (PVP K30) in 20 mL of ethylene glycol, and then add 0.08 g of potassium bromide to the above mixture to obtain a suspension.

(2) The mixture of step (1) was then transferred to the reactor and sealed, and kept at 150 °C for 12 h. After it was naturally cooled to room temperature, it was centrifuged and washed three times with absolute ethanol. Drying to obtain bismuth oxybromide balls.

(3) 50 mg of bismuth oxybromide spheres obtained in step (1), 1.5 g of polyvinylpyrrolidone (PVP K30) and 0.8 g of cobalt nitrate hexahydrate (Co(NO ₃ ) ₂ 6H ₂ O) were dissolved in 20 mL of methanol Stir to dissolve, slowly drop 20 ml of methanol containing 1 g of 2-methylimidazole into the above mixture and stir, after stirring for 60 minutes, the obtained product is collected by centrifugal filtration, and washed three times with deionized water and ethanol.

(4) Dissolve 250 mg of thioacetamide in 15 mL of ethanol, weigh 40 mg of the purple powder product obtained in step (3), add it to the above ethanol solution, transfer it to the reaction kettle, lock it tightly, and place it in an oven for 180 At a constant temperature of ℃, the temperature was kept for 4 hours, and finally the powder was collected by centrifugal filtration, washed three times with deionized water and ethanol, and dried.

(5) Measure 50-80 mg of the powder product obtained in step (2), spread it evenly in a ceramic boat, and then place the ceramic boat in a tube furnace protected by argon and hydrogen for calcination at a calcination temperature of 300 °C and a temperature of 5 Hour. Finally, the multi-cavity cladding structure bismuth sulfide/cobalt sulfide composite electrode material can be prepared after it is naturally cooled to room temperature. Fig. 3 is a scanning electron microscope image of the MOF precursor coated by the oxybromide spheres prepared in Example 3. It can be seen that with the extension of the coating time, the redundant MOF polyhedrons are autonomously formed outside and no longer grow on the bismuth oxybromide spheres. .

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (6)

1. A preparation method of a multi-cavity coating structure bismuth sulfide/cobalt sulfide composite electrode material is characterized by comprising the following steps: firstly, synthesizing bismuth oxybromide spheres at a certain temperature by quantitative bismuth nitrate, potassium bromide and polyvinylpyrrolidone through a reaction kettle, then uniformly coating the surfaces of the bismuth oxybromide spheres with a metal organic frame ZIF-67 polyhedron, vulcanizing by taking thioacetamide as a sulfur source and ethanol as a solvent, and finally calcining to obtain the bismuth sulfide/cobalt sulfide composite electrode material.

2. The method of claim 1, wherein: the method specifically comprises the following steps:

(1) dissolving 0.3-0.6 g of bismuth nitrate pentahydrate and 0.3-0.5 g of polyvinylpyrrolidone in 20mL of ethylene glycol, and then adding 0.08-0.1 g of potassium bromide into the mixture to obtain a suspension;

(2) then transferring the mixture obtained in the step (1) into a reaction kettle, sealing, keeping the reaction kettle at the temperature of 100-150 ℃ for 10-12 hours, after naturally cooling to room temperature, centrifugally washing the reaction kettle for 3-5 times by using absolute ethyl alcohol, and drying the washed product to obtain bismuth oxybromide balls;

(3) stirring and dissolving 30-50 mg of bismuth oxybromide balls obtained in the step (1), 1-2 g of polyvinylpyrrolidone and 0.5-0.8 g of cobalt nitrate hexahydrate in 20mL of methanol, slowly dropping 20mL of methanol containing 0.8-1 g of 2-methylimidazole into the mixture, stirring for 20-30 minutes, centrifugally filtering, collecting obtained purple powder products, washing with deionized water and ethanol for 3-5 times, and drying;

(4) dissolving 100-300 mg of thioacetamide in 15-30 mL of ethanol, weighing 40-60 mg of purple powder product obtained in the step (3), adding the purple powder product into the ethanol solution, transferring the mixture into a reaction kettle, locking, keeping the temperature in an oven at the constant temperature of 150-180 ℃ for 3-4 hours, finally performing centrifugal filtration, collecting the obtained powder product, washing the powder product with deionized water and ethanol for 3-5 times, and drying;

(5) weighing 50-80 mg of the powder product obtained in the step (4), uniformly spreading the powder product in a porcelain boat, and then placing the porcelain boat in a tubular furnace protected by argon and hydrogen for calcination at the calcination temperature of 200-500 ℃ for 1-5 hours; and finally, naturally cooling the electrode to room temperature to obtain the multi-cavity coating structure bismuth sulfide/cobalt sulfide composite electrode material.

3. The method of claim 2, wherein: the mass ratio of bismuth to bromine in the bismuth nitrate pentahydrate and the potassium bromide in the step (1) is 1: 1.

4. The method of claim 2, wherein: the diameter of the bismuth oxybromide sphere in the step (2) is 1.0-2.0 microns.

5. The method of claim 2, wherein: the mass ratio of the cobalt nitrate hexahydrate and the 2-methylimidazole in the step (3) is 1: 8.

6. A multi-cavity coated bismuth sulfide/cobalt sulfide composite electrode material prepared by the preparation method according to any one of claims 1 to 5.

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